This disclosure relates to flame retardant polycarbonate compositions, methods of manufacture thereof and to articles comprising the same.
In electronic and electrical devices such as notebook personal computers, e-books, and tablet personal computers, metallic body panels are being replaced by materials that are lighter in weight and offer a robust combination of mechanical properties. These lighter materials result in weight savings, cost savings, and enable the manufacture of complex designs. While these lighter materials can be used to manufacture panels having thinner cross-sectional thicknesses, it is desirable to improve the stiffness of the material to prevent warping. It is also desirable to improve the flame retardancy of the material to reduce fire related hazards.
Electrical components can be provided as molded injection devices (MID) with desired printed conductors. In contrast to older circuit boards made of fiberglass-reinforced plastic or the like, MID components manufactured in this way are three-dimensional (3D) molded parts having an integrated printed conductor layout and possibly further electronic or electromechanical components. The use of MID components of this type, even if the components have only printed conductors and are used to replace conventional wiring inside an electrical or electronic device, saves space, allowing the relevant device to be made smaller. It also lowers the manufacturing costs by reducing the number of assembly and contacting steps. These MID devices have great utility in cell phones, PDAs and notebook applications.
Stamp metal, flexible printed circuit board (FPCB) mounted, and two-shot molding methods are three existing technologies to make an MID. However, stamping and FPCB mounted process have limitations in the pattern geometry, and the tooling is expensive. Also, altering a RF pattern can cause high-priced and time-consuming modifications in tooling. Two-shot-molding (two-component injection molding) processes have also been used to produce 3D-MIDs with real three-dimensional structures. For example, an antenna can be formed by subsequent chemical corrosion, chemical surface activation, and selective metal coating. This method involves relatively high initial costs and is only economically viable for large production numbers. Two-shot-molding is also not regarded as an environmentally friendly process. All of these three methods are tool-based technologies, which have limited flexibility, long development cycles, difficult prototype, expensive design changes, and limited ability to produce miniaturization. Accordingly, it is becoming increasingly popular to form MIDs using a new laser direct structuring (LDS) process. In an LDS process a computer-controlled laser beam travels over the MID to activate the plastic surface at locations where the conductive path is to be situated.
Laser-supported or directed structuring process (LDS) for 3D MIDs simplifies the manufacturing process. For example, the LDS process allows for antenna structures to be directly and cost effectively integrated into the cell phone housing. Further, the LDS process allows for sophisticated mechatronic systems that integrate mechanical and electrical properties for automotive and medical applications. With a laser direct structuring process, it is also possible to obtain small conductive path widths (such as 150 microns or less). In addition, the spacing between the conductive paths can also be small. As a result, MIDs formed from this process can save space and weight in end-use applications. Another advantage of laser direct structuring is its flexibility. If the design of the circuit is to be changed, it is simply a matter of reprogramming the computer that controls the laser.
In summary, LDS process is a promising approach that is getting more and more popular for metalizing only partial areas of three-dimensional plastic surfaces by selective activation followed by selective metal deposition through chemical plating processes. When using special substrate materials, laser irradiation can directly trigger such a selective activation. To further expand the application of this LDS technology, high performance materials are desired with also good flame retardancy as well as LDS functionality for emerging applications which still use traditional MID process, such as, for example, a notebook antenna.